Find Peak Element

Leetcode Problem 162: Find Peak Element

Problem Summary

A peak element is an element that is strictly greater than its immediate neighbors. Given a 0-indexed integer array nums, find any peak element and return its index. The array boundaries behave as negative infinity — the first and last elements only need to be greater than their single neighbour to qualify as a peak.

Your solution must run in O(log n) time.

Constraints:

• The array has between 1 and 1,000 elements.
• Each element is a 32-bit signed integer, and no two adjacent elements are equal.

Techniques

• Array
• Binary Search

Solution

function findPeakElement(nums: number[]): number {
    let left = 0;
    let right = nums.length - 1;

    while (left < right) {
        let mid = left + Math.floor((right - left) / 2);

        if (nums[mid] > nums[mid + 1]) {
            right = mid;
        } else {
            left = mid + 1;
        }
    }

    return left;
}

console.log(findPeakElement([1,2,1,3,5,6,4]))